docs: def colorscale(mag, cmin, cmax):
      """
      Return a tuple of floats between 0 and 1 for R, G, and B.
      From Python Cookbook (9.11?)
      """
      # Normalize to 0-1
      try:
          x = float(mag-cmin)/(cmax-cmin)
      except ZeroDivisionError:
          x = 0.5  # cmax == cmin
      blue = min((max((4*(0.75-x), 0.)), 1.))
      red = min((max((4*(x-0.25), 0.)), 1.))
      green = min((max((4*abs(x-0.5)-1., 0.)), 1.))
      return red, green, blue